DE 10 2008 043 367 A1 discloses a hybrid drive device for a motor vehicle, having an internal combustion engine and an electric motor, in each case for driving the motor vehicle. A rotor of the electric motor is arranged on a hollow shaft in the drivetrain. Means for conveying a cooling fluid convey said cooling fluid through the inner space of the hollow shaft in order to cool the rotor and the hollow shaft.
Cooling fins are arranged in the inner space of the hollow shaft in order to transfer the heat to the cooling fluid in the best way possible. The cooling fins are formed integrally on the inner wall of the hollow shaft in a fairly complex manner. Also, the inner diameter of the hollow shaft, and thus the diameter of the region which is able to be used for the cooling, is quite small in size, this resulting in a limited cooling performance.
Thus a need exists for a hollow shaft arrangement that offers a simple construction, very good cooling behavior and ease of assembly.